Why are coral reefs being destroyed?

Coral reefs are among the most biodiverse ecosystems on Earth. They cover only 0.1% of the area of the ocean but contain at least 25% of all species in the marine environment.

The corals themselves are known as “mutualistic symbioses”. Symbiosis is a relationship between two or more organisms that live in the same place.

The coral symbiosis is between a polyp, which is an animal closely related to a jellyfish, and a group of microorganisms called zooxanthellae, which are part of a very common marine group known as the dinoflagellates.

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This relationship is mutualistic because both the polyps and zooxanthellae gain a mutual benefit from interacting with each other. In fact, the two organisms do so well that they are able to support an enormous diversity of other species.

Resilience and resistance of coral reef ecosystems

Dr Maria Beger is a University Academic Fellow in Marine Conservation Science at the University of Leeds, where her research focuses on the conservation of coral reefs by identifying and prioritising the most biodiverse areas for protection in marine reserves.

Maria introduces you to marine ecosystems in the video, and explores some of the reasons behind coral reef destruction.

Two key concepts that she introduces are resistance and resilience of ecosystems.

Resistance is how well an ecosystem resists the stressors that are put on it. For a coral reef, this could be how well coral resists an increase in water temperature as a result of climate change.

Resilience is how long it takes an ecosystem to recover after a disturbance. If an area of coral reef is damaged by fishing, resilience would describe how quickly it would recover from the damage.

Have your say:

• Out of the threats described by Maria, which do you think is the most significant to coral reefs, and why?
• Which threat do you think would be the most difficult to resolve?

Share and discuss your responses with other learners in the Comments section. Have you identified any human interactions not discussed in the video?